A(4) Flavor Symmetry Model for Dirac-Neutrinos and Sizable U(e3)

TL;DR

This paper presents an A(4) flavor symmetry model for Dirac neutrinos that naturally explains a sizable U(e3) mixing angle, linking neutrino nature to deviations from tri-bimaximal mixing.

Contribution

It introduces a novel A(4) flavor symmetry model for Dirac neutrinos within a neutrinophilic 2 Higgs doublet framework, connecting neutrino type to mixing deviations.

Findings

The model predicts a non-zero U(e3) angle consistent with experimental data.

Dirac neutrinos lead to anti-symmetric contributions, causing deviations from tri-bimaximal mixing.

The framework links neutrino nature to observable lepton mixing parameters.

Abstract

Models based on flavor symmetries are the most often studied approaches to explain the unexpected structure of lepton mixing. In many flavor symmetry groups a product of two triplet representations contains a symmetric and an anti-symmetric term. If this product of two triplets corresponds to a Majorana mass term, then the anti-symmetric part vanishes, and in economic models tri-bimaximal mixing is achieved. If neutrinos are Dirac particles, the anti-symmetric part is however present and leads to deviations from tri-bimaximal mixing, in particular non-zero U(e3). Thus, the non-vanishing value of U(e3) and the nature of the neutrino are connected. We illustrate this with a model based on A(4) within the framework of a neutrinophilic 2 Higgs doublet scenario.